what do i use if not an if statement

Your code is actually not quite right (even ignoring the use of the if statement) but it's close enough that the code checker mistakenly thinks it's right.

When you pass an argument to a method (like indexOf) you shouldn't specify the type of the argument, the type is only specified when you define a parameter or variable, so you should not include the char keyword in your call to indexOf.

Also the expression tiles.indexOf(tile) != -1 returns True if the tile is present in the tiles string and False otherwise, so inside your if statement you should actually return True not False, and vice versa for the return statement you have placed outside the if statement.

With those two changes your code would work, but as the challenge checker hints at it's not actually necessary to use an if statement for this challenge. As I mentioned above the tiles.indexOf(tile) != -1 expression evaluates to True or False on it's own, which means that you can return it directly without using an if statement.

Like this:

public class ScrabblePlayer {
  // A String representing all of the tiles that this player has
  private String tiles;

  public ScrabblePlayer() {
    tiles = "";
  }

  public String getTiles() {
    return tiles;
  }

  public void addTile(char tile) {
    tiles += tile;

  }

  public boolean hasTile(char tile) {
    // TODO: Determine if user has the tile passed in
    return tiles.indexOf(tile) != -1;
  }
}